The present invention relates to a reprogrammable RAM cartridge for use in a microprocessor based system. In particular, it relates to a reprogrammable cartridge of the type which can be used to replace a fixed program cartridge of the type typically found in video games.
Many microprocessor based systems, such as video games, rely upon a memory cartridge which typically contains some type of read only memory (ROM). The ROM may be either a mask programmable ROM, meaning that the program contained therein is placed in the ROM at the time of its manufacture, or the ROM may be reprogrammable after erasure either via the use of an ultraviolet light, in the case of what is commonly called an eraseable programmable read only memory (EPROM), or via the use of an electrical signal, in the case of what is commonly called an electrically eraseable programmable read only memory (EE-PROM) or an electrically alterable read only memory (EAROM). As used herein, the term "ROM" will refer to the standard mask programmable ROM unless otherwise specified.
While a ROM provides the lowest unit cost of manufacturing memory cartridges, assuming that the volume is large enough to justify the initial outlay to create the special purpose mask used in manufacturing the ROM, a ROM cannot be reprogrammed once it has been manufactured. Accordingly, each game cartridge, in the case of a video game, is dedicated from the time of its manufacture. Any change in games, or any change in the program of a particular game, requires a new game cartridge containing a new ROM. As the unit price of a game cartridge is determined by a combination of factors, including license fees, cost of manufacture, and cost of distribution, the collection of a number of game cartridges becomes very expensive for the game owner. This is unfortunate, because old games eventually become obsolete or boring, and continuous replacement of old games becomes expensive and tiresome.
Efforts on the part of third party suppliers to produce new, inexpensive games have heretofore been impeded to some extent by a variety of tactics employed by the game manufacturers. These tactics include restricting the distribution of information regarding the manner in which the games operate, and manufacturing cartridges which have a plug configuration, i.e. a pinout, which prevents them from being readily connected to a device other than the manufacturer's video game unit. Thus, even if one were to want to design a game cartridge which contained a reprogrammable memory unit, its design would be complicated by the current design of typical game cartridges. Accordingly, it would be desirable to be able to produce a reprogrammable game cartridge which could be used in conjunction with standard types of video games.